/*
 * Date Format 1.2.3
 * (c) 2007-2009 Steven Levithan <stevenlevithan.com>
 * MIT license
 *
 * Includes enhancements by Scott Trenda <scott.trenda.net>
 * and Kris Kowal <cixar.com/~kris.kowal/>
 *
 * Accepts a date, a mask, or a date and a mask.
 * Returns a formatted version of the given date.
 * The date defaults to the current date/time.
 * The mask defaults to masks.default.
 */

// Regexes and supporting functions are cached through closure
const token = /d{1,4}|D{3,4}|m{1,4}|yy(?:yy)?|([HhMsTt])\1?|W{1,2}|[LlopSZN]|"[^"]*"|'[^']*'/g
const timezone = /\b(?:[A-Z]{1,3}[A-Z][TC])(?:[-+]\d{4})?|((?:Australian )?(?:Pacific|Mountain|Central|Eastern|Atlantic) (?:Standard|Daylight|Prevailing) Time)\b/g
const timezoneClip = /[^-+\dA-Z]/g

/**
 * @param {string | number | Date} date
 * @param {string} mask
 * @param {boolean} utc
 * @param {boolean} gmt
 */
export default function dateFormat (date, mask, utc, gmt) {
    // You can't provide utc if you skip other args (use the 'UTC:' mask prefix)
    if (
        arguments.length === 1 &&
    typeof date === 'string' &&
    !/\d/.test(date)
    ) {
        mask = date
        date = undefined
    }

    date = date || date === 0 ? date : new Date()

    if (!(date instanceof Date)) {
        date = new Date(date)
    }

    if (isNaN(date)) {
        throw TypeError('Invalid date')
    }

    mask = String(
        masks[mask] || mask || masks.default
    )

    // Allow setting the utc/gmt argument via the mask
    const maskSlice = mask.slice(0, 4)
    if (maskSlice === 'UTC:' || maskSlice === 'GMT:') {
        mask = mask.slice(4)
        utc = true
        if (maskSlice === 'GMT:') {
            gmt = true
        }
    }

    const _ = () => (utc ? 'getUTC' : 'get')
    const d = () => date[_() + 'Date']()
    const D = () => date[_() + 'Day']()
    const m = () => date[_() + 'Month']()
    const y = () => date[_() + 'FullYear']()
    const H = () => date[_() + 'Hours']()
    const M = () => date[_() + 'Minutes']()
    const s = () => date[_() + 'Seconds']()
    const L = () => date[_() + 'Milliseconds']()
    const o = () => (utc ? 0 : date.getTimezoneOffset())
    const W = () => getWeek(date)
    const N = () => getDayOfWeek(date)

    const flags = {
        d: () => d(),
        dd: () => pad(d()),
        ddd: () => i18n.dayNames[D()],
        DDD: () => getDayName({
            y: y(),
            m: m(),
            d: d(),
            _: _(),
            dayName: i18n.dayNames[D()],
            short: true
        }),
        dddd: () => i18n.dayNames[D() + 7],
        DDDD: () => getDayName({
            y: y(),
            m: m(),
            d: d(),
            _: _(),
            dayName: i18n.dayNames[D() + 7]
        }),
        m: () => m() + 1,
        mm: () => pad(m() + 1),
        mmm: () => i18n.monthNames[m()],
        mmmm: () => i18n.monthNames[m() + 12],
        yy: () => String(y()).slice(2),
        yyyy: () => pad(y(), 4),
        h: () => H() % 12 || 12,
        hh: () => pad(H() % 12 || 12),
        H: () => H(),
        HH: () => pad(H()),
        M: () => M(),
        MM: () => pad(M()),
        s: () => s(),
        ss: () => pad(s()),
        l: () => pad(L(), 3),
        L: () => pad(Math.floor(L() / 10)),
        t: () =>
            H() < 12
                ? i18n.timeNames[0]
                : i18n.timeNames[1],
        tt: () =>
            H() < 12
                ? i18n.timeNames[2]
                : i18n.timeNames[3],
        T: () =>
            H() < 12
                ? i18n.timeNames[4]
                : i18n.timeNames[5],
        TT: () =>
            H() < 12
                ? i18n.timeNames[6]
                : i18n.timeNames[7],
        Z: () =>
            gmt
                ? 'GMT'
                : utc
                    ? 'UTC'
                    : formatTimezone(date),
        o: () =>
            (o() > 0 ? '-' : '+') +
      pad(Math.floor(Math.abs(o()) / 60) * 100 + (Math.abs(o()) % 60), 4),
        p: () =>
            (o() > 0 ? '-' : '+') +
      pad(Math.floor(Math.abs(o()) / 60), 2) +
      ':' +
      pad(Math.floor(Math.abs(o()) % 60), 2),
        S: () =>
            ['th', 'st', 'nd', 'rd'][
                d() % 10 > 3 ? 0 : (((d() % 100) - (d() % 10) !== 10) * d()) % 10
            ],
        W: () => W(),
        WW: () => pad(W()),
        N: () => N()
    }

    return mask.replace(token, (match) => {
        if (match in flags) {
            return flags[match]()
        }
        return match.slice(1, match.length - 1)
    })
}

export const masks = {
    default: 'ddd mmm dd yyyy HH:MM:ss',
    shortDate: 'm/d/yy',
    paddedShortDate: 'mm/dd/yyyy',
    mediumDate: 'mmm d, yyyy',
    longDate: 'mmmm d, yyyy',
    fullDate: 'dddd, mmmm d, yyyy',
    shortTime: 'h:MM TT',
    mediumTime: 'h:MM:ss TT',
    longTime: 'h:MM:ss TT Z',
    isoDate: 'yyyy-mm-dd',
    isoTime: 'HH:MM:ss',
    isoDateTime: "yyyy-mm-dd'T'HH:MM:sso",
    isoUtcDateTime: "UTC:yyyy-mm-dd'T'HH:MM:ss'Z'",
    expiresHeaderFormat: 'ddd, dd mmm yyyy HH:MM:ss Z'
}

// Internationalization strings
export const i18n = {
    dayNames: [
        'Sun',
        'Mon',
        'Tue',
        'Wed',
        'Thu',
        'Fri',
        'Sat',
        'Sunday',
        'Monday',
        'Tuesday',
        'Wednesday',
        'Thursday',
        'Friday',
        'Saturday'
    ],
    monthNames: [
        'Jan',
        'Feb',
        'Mar',
        'Apr',
        'May',
        'Jun',
        'Jul',
        'Aug',
        'Sep',
        'Oct',
        'Nov',
        'Dec',
        'January',
        'February',
        'March',
        'April',
        'May',
        'June',
        'July',
        'August',
        'September',
        'October',
        'November',
        'December'
    ],
    timeNames: ['a', 'p', 'am', 'pm', 'A', 'P', 'AM', 'PM']
}

const pad = (val, len = 2) => String(val).padStart(len, '0')

/**
 * Get day name
 * Yesterday, Today, Tomorrow if the date lies within, else fallback to Monday - Sunday
 * @param  {Object}
 * @return {String}
 */
const getDayName = ({ y, m, d, _, dayName, short = false }) => {
    const today = new Date()
    const yesterday = new Date()
    yesterday.setDate(yesterday[_ + 'Date']() - 1)
    const tomorrow = new Date()
    tomorrow.setDate(tomorrow[_ + 'Date']() + 1)
    const today_d = () => today[_ + 'Date']()
    const today_m = () => today[_ + 'Month']()
    const today_y = () => today[_ + 'FullYear']()
    const yesterday_d = () => yesterday[_ + 'Date']()
    const yesterday_m = () => yesterday[_ + 'Month']()
    const yesterday_y = () => yesterday[_ + 'FullYear']()
    const tomorrow_d = () => tomorrow[_ + 'Date']()
    const tomorrow_m = () => tomorrow[_ + 'Month']()
    const tomorrow_y = () => tomorrow[_ + 'FullYear']()

    if (today_y() === y && today_m() === m && today_d() === d) {
        return short ? 'Tdy' : 'Today'
    } else if (yesterday_y() === y && yesterday_m() === m && yesterday_d() === d) {
        return short ? 'Ysd' : 'Yesterday'
    } else if (tomorrow_y() === y && tomorrow_m() === m && tomorrow_d() === d) {
        return short ? 'Tmw' : 'Tomorrow'
    }
    return dayName
}

/**
 * Get the ISO 8601 week number
 * Based on comments from
 * http://techblog.procurios.nl/k/n618/news/view/33796/14863/Calculate-ISO-8601-week-and-year-in-javascript.html
 *
 * @param  {Date} `date`
 * @return {Number}
 */
const getWeek = (date) => {
    // Remove time components of date
    const targetThursday = new Date(
        date.getFullYear(),
        date.getMonth(),
        date.getDate()
    )

    // Change date to Thursday same week
    targetThursday.setDate(
        targetThursday.getDate() - ((targetThursday.getDay() + 6) % 7) + 3
    )

    // Take January 4th as it is always in week 1 (see ISO 8601)
    const firstThursday = new Date(targetThursday.getFullYear(), 0, 4)

    // Change date to Thursday same week
    firstThursday.setDate(
        firstThursday.getDate() - ((firstThursday.getDay() + 6) % 7) + 3
    )

    // Check if daylight-saving-time-switch occurred and correct for it
    const ds =
    targetThursday.getTimezoneOffset() - firstThursday.getTimezoneOffset()
    targetThursday.setHours(targetThursday.getHours() - ds)

    // Number of weeks between target Thursday and first Thursday
    const weekDiff = (targetThursday - firstThursday) / (86400000 * 7)
    return 1 + Math.floor(weekDiff)
}

/**
 * Get ISO-8601 numeric representation of the day of the week
 * 1 (for Monday) through 7 (for Sunday)
 *
 * @param  {Date} `date`
 * @return {Number}
 */
const getDayOfWeek = (date) => {
    let dow = date.getDay()
    if (dow === 0) {
        dow = 7
    }
    return dow
}

/**
 * Get proper timezone abbreviation or timezone offset.
 *
 * This will fall back to `GMT+xxxx` if it does not recognize the
 * timezone within the `timezone` RegEx above. Currently only common
 * American and Australian timezone abbreviations are supported.
 *
 * @param  {String | Date} date
 * @return {String}
 */
export const formatTimezone = (date) => {
    return (String(date).match(timezone) || [''])
        .pop()
        .replace(timezoneClip, '')
        .replace(/GMT\+0000/g, 'UTC')
}
